The present invention relates to a heat exchanger, especially for devices operated with great load and/or temperature changes, for example, as a cooling air cooling device for gas turbines, with tubes for separating the heat-transferring medium, especially air, and the heat-receiving medium, especially water. The heat exchange is carried out in counter flow. The flow channels for the heat-receiving medium in the form of tubes extend meander-shaped between a common inlet pipe and a common outlet pipe, and the heat-transferring medium flows along the exterior of the meander-shaped tubes.
The cooling of gas turbine blades is carried out conventionally with an air stream which is often branched off the compressed combustion air for the gas turbine furnace chamber as a partial air stream. The heat energy that has been introduced into the partial air stream by compression must be removed from the air stream before being guided to the gas turbine blades in a cooling air cooling device. Due to frequent start-up and shut-down operations as well as due to the high pressure and temperature differences, this heat exchanger is subjected to extreme load changes which may result in a premature failure of the heat exchanger. A cooling air cooler of the aforementioned kind is known from European document 0 203 445. In this heat exchanger the common inlet and outlet pipes are fixedly connected with the clean gas inlet, respectively, clean gas outlet lines so that load changes and the resulting stress can be compensated only to an insufficient degree.
A further cooling air cooler for gas turbines is known from German Offenlegungsschrift 41 42 375.5. In this known heat exchanger, massive tube plates serve to partition the air-filled chambers from a chamber containing a heat-receiving medium. The air to be cooled is guided through tubes that connect the massive tube plates at the upper and lower end of the heat exchanger and that are fixedly mounted therein. For compensation of the occurring pressure and temperature stresses in these known heat exchangers, one of the massive tube plates is clamped only at one side so that pressure and temperature stresses can be compensated to a certain extent. Furthermore, the outer mantle of the heat exchanger is provided with bellows-type compensators for damping occurring length changes. This known heat exchanger allows to a certain extent a compensation of the pressure and temperature fluctuations resulting from frequent and fast load changes; however, the rigid clamping of the heat exchanger tubes between the two massive tube plates prevents an effective damping of these stresses. Furthermore, the use of the massive tube plates is disadvantageous due to their high weight and their inflexibilty relative to temperature stresses.
It is therefore an object of the present invention to improve a heat exchanger of the aforementioned kind such that the resulting frequent and fast load changes and the resulting pressure and temperature fluctuations can be compensated in a secure and reliable manner. Furthermore, the heat exchanger should be inexpensive to manufacture.